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Re: new compiler warning with bison 2.6.5 (PostgreSQL)
|
From: |
Akim Demaille |
|
Subject: |
Re: new compiler warning with bison 2.6.5 (PostgreSQL) |
|
Date: |
Mon, 26 Nov 2012 09:57:38 +0100 |
Le 23 nov. 2012 à 15:46, Akim Demaille <address@hidden> a écrit :
> commit fb4c8a7cb97844f6c66921a77e79311a19d12fc2
> Author: Theophile Ranquet <address@hidden>
> Date: Mon Nov 19 10:43:56 2012 +0000
>
> yacc.c: always initialize yylloc
>
> The initial location might be used if the parser starts by an empty
> reduction, so really ensure proper initialization of the initial
> location. The previous approach fails for PostgreSQL, which uses
> Reported by Peter Eisentraut.
> http://lists.gnu.org/archive/html/bug-bison/2012-11/msg00023.html
> With help from Théophile Ranquet.
>
> * data/yacc.c (b4_declare_scanner_communication_variables): Be sure
> to initialize yylloc, even when its structure is unknown.
> (yyparse): Simplify the call to b4_dollar_pushdef.
> * tests/actions.at (Initial location): Check of similar pattern
> as in the case of PostgreSQL.
Installed and merge into maint as follows.
commit c6bf97ccb45672a004ef376b9f3e578d2f558d5f
Merge: 68ac70b fb4c8a7
Author: Akim Demaille <address@hidden>
Date: Mon Nov 26 09:05:28 2012 +0100
Merge remote-tracking branch 'origin/branch-2.6' into maint
* origin/branch-2.6:
yacc.c: always initialize yylloc
doc: one of the fixes for an ambiguous grammar was ambiguous too
doc: fix the dangling else with precedence directives
doc: prefer "token" to TOKEN
doc: formatting changes
Conflicts:
NEWS
doc/bison.texi
diff --git a/NEWS b/NEWS
index 46d614c..3789e92 100644
--- a/NEWS
+++ b/NEWS
@@ -56,6 +56,17 @@ GNU Bison NEWS
Two nodes were added to the documentation: Xml and Graphviz.
+* Noteworthy changes in release ?.? (????-??-??) [?]
+
+** Bug fixes
+
+ Warnings about uninitialized yylloc in yyparse have been fixed.
+
+** Documentation
+
+ The sections about shift/reduce and reduce/reduce conflicts resolution
+ have been fixed and extended.
+
* Noteworthy changes in release 2.6.5 (2012-11-07) [stable]
We consider compiler warnings about Bison generated parsers to be bugs.
diff --git a/THANKS b/THANKS
index ecdd1a8..8ae024f 100644
--- a/THANKS
+++ b/THANKS
@@ -1,8 +1,9 @@
Bison was originally written by Robert Corbett. It would not be what
it is today without the invaluable help of these people:
+Аскар Сафин address@hidden
Airy Andre address@hidden
-Akim Demaille address@hidden
+Akim Demaille address@hidden
Albert Chin-A-Young address@hidden
Alexander Belopolsky address@hidden
Alexandre Duret-Lutz address@hidden
@@ -88,6 +89,7 @@ Pascal Bart address@hidden
Paul Eggert address@hidden
Paul Hilfinger address@hidden
Per Allansson address@hidden
+Peter Eisentraut address@hidden
Peter Fales address@hidden
Peter Hamorsky address@hidden
Peter Simons address@hidden
diff --git a/data/yacc.c b/data/yacc.c
index 2e0ecc2..bbc9d91 100644
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -184,7 +184,8 @@ int yychar;
or non-GCC compilers. */
static YYSTYPE yyval_default;
# define YY_INITIAL_VALUE(Value) = Value
-#endif]])[
+#endif]b4_locations_if([[
+static YYLTYPE yyloc_default][]b4_yyloc_default[;]])])[
#ifndef YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
# define YY_IGNORE_MAYBE_UNINITIALIZED_END
@@ -197,7 +198,7 @@ static YYSTYPE yyval_default;
YYSTYPE yylval YY_INITIAL_VALUE(yyval_default);]b4_locations_if([[
/* Location data for the lookahead symbol. */
-YYLTYPE yylloc][]b4_yyloc_default[;
+YYLTYPE yylloc]b4_pure_if([ = yyloc_default], [b4_yyloc_default])[;
]])b4_pure_if([], [[
/* Number of syntax errors so far. */
@@ -1410,7 +1411,8 @@ b4_c_function_def([[yyparse]], [[int]], b4_parse_param)[
yypstate *yyps_local;]b4_pure_if([[
int yychar;
YYSTYPE yylval;]b4_locations_if([[
- YYLTYPE yylloc][]b4_yyloc_default[;]])])[
+ static YYLTYPE yyloc_default][]b4_yyloc_default[;
+ YYLTYPE yylloc = yyloc_default;]])])[
if (yyps)
yyps_local = yyps;
else
@@ -1559,8 +1561,7 @@ b4_c_function_def([[yyparse]], [[int]], b4_parse_param)[
yychar = YYEMPTY; /* Cause a token to be read. */
]m4_ifdef([b4_initial_action], [
b4_dollar_pushdef([m4_define([b4_dollar_dollar_used])yylval], [],
- [m4_define([b4_at_dollar_used])dnl
-b4_push_if([b4_pure_if([*])yypushed_loc], [yylloc])])dnl
+ [b4_push_if([b4_pure_if([*])yypushed_loc], [yylloc])])dnl
/* User initialization code. */
b4_user_initial_action
b4_dollar_popdef[]dnl
diff --git a/doc/bison.texi b/doc/bison.texi
index 7bb4146..f2d3dbc 100644
--- a/doc/bison.texi
+++ b/doc/bison.texi
@@ -276,6 +276,7 @@ Operator Precedence
* Using Precedence:: How to specify precedence in Bison grammars.
* Precedence Examples:: How these features are used in the previous example.
* How Precedence:: How they work.
+* Non Operators:: Using precedence for general conflicts.
Tuning LR
@@ -6598,7 +6599,7 @@ expr:
term:
'(' expr ')'
| term '!'
-| NUMBER
+| "number"
;
@end group
@end example
@@ -6637,20 +6638,20 @@ statements, with a pair of rules like this:
@example
@group
if_stmt:
- IF expr THEN stmt
-| IF expr THEN stmt ELSE stmt
+ "if" expr "then" stmt
+| "if" expr "then" stmt "else" stmt
;
@end group
@end example
@noindent
-Here we assume that @code{IF}, @code{THEN} and @code{ELSE} are
-terminal symbols for specific keyword tokens.
+Here @code{"if"}, @code{"then"} and @code{"else"} are terminal symbols for
+specific keyword tokens.
-When the @code{ELSE} token is read and becomes the lookahead token, the
+When the @code{"else"} token is read and becomes the lookahead token, the
contents of the stack (assuming the input is valid) are just right for
reduction by the first rule. But it is also legitimate to shift the
address@hidden, because that would lead to eventual reduction by the second
address@hidden"else"}, because that would lead to eventual reduction by the
second
rule.
This situation, where either a shift or a reduction would be valid, is
@@ -6659,14 +6660,14 @@ these conflicts by choosing to shift, unless otherwise
directed by
operator precedence declarations. To see the reason for this, let's
contrast it with the other alternative.
-Since the parser prefers to shift the @code{ELSE}, the result is to attach
+Since the parser prefers to shift the @code{"else"}, the result is to attach
the else-clause to the innermost if-statement, making these two inputs
equivalent:
@example
-if x then if y then win (); else lose;
+if x then if y then win; else lose;
-if x then do; if y then win (); else lose; end;
+if x then do; if y then win; else lose; end;
@end example
But if the parser chose to reduce when possible rather than shift, the
@@ -6674,9 +6675,9 @@ result would be to attach the else-clause to the
outermost if-statement,
making these two inputs equivalent:
@example
-if x then if y then win (); else lose;
+if x then if y then win; else lose;
-if x then do; if y then win (); end; else lose;
+if x then do; if y then win; end; else lose;
@end example
The conflict exists because the grammar as written is ambiguous: either
@@ -6689,11 +6690,16 @@ This particular ambiguity was first encountered in the
specifications of
Algol 60 and is called the ``dangling @code{else}'' ambiguity.
To avoid warnings from Bison about predictable, legitimate shift/reduce
-conflicts, use the @code{%expect @var{n}} declaration.
+conflicts, you can use the @code{%expect @var{n}} declaration.
There will be no warning as long as the number of shift/reduce conflicts
is exactly @var{n}, and Bison will report an error if there is a
different number.
address@hidden Decl, ,Suppressing Conflict Warnings}.
address@hidden Decl, ,Suppressing Conflict Warnings}. However, we don't
+recommend the use of @code{%expect} (except @samp{%expect 0}!), as an equal
+number of conflicts does not mean that they are the @emph{same}. When
+possible, you should rather use precedence directives to @emph{fix} the
+conflicts explicitly (@pxref{Non Operators,, Using Precedence For Non
+Operators}).
The definition of @code{if_stmt} above is solely to blame for the
conflict, but the conflict does not actually appear without additional
@@ -6702,7 +6708,6 @@ the conflict:
@example
@group
-%token IF THEN ELSE variable
%%
@end group
@group
@@ -6714,13 +6719,13 @@ stmt:
@group
if_stmt:
- IF expr THEN stmt
-| IF expr THEN stmt ELSE stmt
+ "if" expr "then" stmt
+| "if" expr "then" stmt "else" stmt
;
@end group
expr:
- variable
+ "identifier"
;
@end example
@@ -6739,6 +6744,7 @@ shift and when to reduce.
* Using Precedence:: How to specify precedence in Bison grammars.
* Precedence Examples:: How these features are used in the previous example.
* How Precedence:: How they work.
+* Non Operators:: Using precedence for general conflicts.
@end menu
@node Why Precedence
@@ -6826,16 +6832,11 @@ would declare them in groups of equal precedence. For
example, @code{'+'} is
declared with @code{'-'}:
@example
-%left '<' '>' '=' NE LE GE
+%left '<' '>' '=' "!=" "<=" ">="
%left '+' '-'
%left '*' '/'
@end example
address@hidden
-(Here @code{NE} and so on stand for the operators for ``not equal''
-and so on. We assume that these tokens are more than one character long
-and therefore are represented by names, not character literals.)
-
@node How Precedence
@subsection How Precedence Works
@@ -6858,6 +6859,44 @@ resolved.
Not all rules and not all tokens have precedence. If either the rule or
the lookahead token has no precedence, then the default is to shift.
address@hidden Non Operators
address@hidden Using Precedence For Non Operators
+
+Using properly precedence and associativity directives can help fixing
+shift/reduce conflicts that do not involve arithmetics-like operators. For
+instance, the ``dangling @code{else}'' problem (@pxref{Shift/Reduce, ,
+Shift/Reduce Conflicts}) can be solved elegantly in two different ways.
+
+In the present case, the conflict is between the token @code{"else"} willing
+to be shifted, and the rule @samp{if_stmt: "if" expr "then" stmt}, asking
+for reduction. By default, the precedence of a rule is that of its last
+token, here @code{"then"}, so the conflict will be solved appropriately
+by giving @code{"else"} a precedence higher than that of @code{"then"}, for
+instance as follows:
+
address@hidden
address@hidden
+%nonassoc "then"
+%nonassoc "else"
address@hidden group
address@hidden example
+
+Alternatively, you may give both tokens the same precedence, in which case
+associativity is used to solve the conflict. To preserve the shift action,
+use right associativity:
+
address@hidden
+%right "then" "else"
address@hidden example
+
+Neither solution is perfect however. Since Bison does not provide, so far,
+support for ``scoped'' precedence, both force you to declare the precedence
+of these keywords with respect to the other operators your grammar.
+Therefore, instead of being warned about new conflicts you would be unaware
+of (e.g., a shift/reduce conflict due to @samp{if test then 1 else 2 + 3}
+being ambiguous: @samp{if test then 1 else (2 + 3)} or @samp{(if test then 1
+else 2) + 3}?), the conflict will be already ``fixed''.
+
@node Contextual Precedence
@section Context-Dependent Precedence
@cindex context-dependent precedence
@@ -7018,30 +7057,38 @@ reduce/reduce conflict must be studied and usually
eliminated. Here is the
proper way to define @code{sequence}:
@example
address@hidden
sequence:
/* empty */ @{ printf ("empty sequence\n"); @}
| sequence word @{ printf ("added word %s\n", $2); @}
;
address@hidden group
@end example
Here is another common error that yields a reduce/reduce conflict:
@example
sequence:
address@hidden
/* empty */
| sequence words
| sequence redirects
;
address@hidden group
address@hidden
words:
/* empty */
| words word
;
address@hidden group
address@hidden
redirects:
/* empty */
| redirects redirect
;
address@hidden group
@end example
@noindent
@@ -7094,6 +7141,58 @@ redirects:
@end group
@end example
+Yet this proposal introduces another kind of ambiguity! The input
address@hidden word} can be parsed as a single @code{words} composed of two
address@hidden, or as two address@hidden @code{words} (and likewise for
address@hidden/@code{redirects}). However this ambiguity is now a
+shift/reduce conflict, and therefore it can now be addressed with precedence
+directives.
+
+To simplify the matter, we will proceed with @code{word} and @code{redirect}
+being tokens: @code{"word"} and @code{"redirect"}.
+
+To prefer the longest @code{words}, the conflict between the token
address@hidden"word"} and the rule @samp{sequence: sequence words} must be
resolved
+as a shift. To this end, we use the same techniques as exposed above, see
address@hidden Operators,, Using Precedence For Non Operators}. One solution
+relies on precedences: use @code{%prec} to give a lower precedence to the
+rule:
+
address@hidden
+%nonassoc "word"
+%nonassoc "sequence"
+%%
address@hidden
+sequence:
+ /* empty */
+| sequence word %prec "sequence"
+| sequence redirect %prec "sequence"
+;
address@hidden group
+
address@hidden
+words:
+ word
+| words "word"
+;
address@hidden group
address@hidden example
+
+Another solution relies on associativity: provide both the token and the
+rule with the same precedence, but make them right-associative:
+
address@hidden
+%right "word" "redirect"
+%%
address@hidden
+sequence:
+ /* empty */
+| sequence word %prec "word"
+| sequence redirect %prec "redirect"
+;
address@hidden group
address@hidden example
+
@node Mysterious Conflicts
@section Mysterious Conflicts
@cindex Mysterious Conflicts
@@ -7103,8 +7202,6 @@ Here is an example:
@example
@group
-%token ID
-
%%
def: param_spec return_spec ',';
param_spec:
@@ -7119,10 +7216,10 @@ return_spec:
;
@end group
@group
-type: ID;
+type: "id";
@end group
@group
-name: ID;
+name: "id";
name_list:
name
| name ',' name_list
@@ -7130,16 +7227,16 @@ name_list:
@end group
@end example
-It would seem that this grammar can be parsed with only a single token
-of lookahead: when a @code{param_spec} is being read, an @code{ID} is
-a @code{name} if a comma or colon follows, or a @code{type} if another
address@hidden follows. In other words, this grammar is LR(1).
+It would seem that this grammar can be parsed with only a single token of
+lookahead: when a @code{param_spec} is being read, an @code{"id"} is a
address@hidden if a comma or colon follows, or a @code{type} if another
address@hidden"id"} follows. In other words, this grammar is LR(1).
@cindex LR
@cindex LALR
However, for historical reasons, Bison cannot by default handle all
LR(1) grammars.
-In this grammar, two contexts, that after an @code{ID} at the beginning
+In this grammar, two contexts, that after an @code{"id"} at the beginning
of a @code{param_spec} and likewise at the beginning of a
@code{return_spec}, are similar enough that Bison assumes they are the
same.
@@ -7170,27 +7267,24 @@ distinct. In the above example, adding one rule to
@example
@group
-%token BOGUS
address@hidden
-%%
@dots{}
return_spec:
type
| name ':' type
-| ID BOGUS /* This rule is never used. */
+| "id" "bogus" /* This rule is never used. */
;
@end group
@end example
This corrects the problem because it introduces the possibility of an
-additional active rule in the context after the @code{ID} at the beginning of
+additional active rule in the context after the @code{"id"} at the beginning of
@code{return_spec}. This rule is not active in the corresponding context
in a @code{param_spec}, so the two contexts receive distinct parser states.
-As long as the token @code{BOGUS} is never generated by @code{yylex},
+As long as the token @code{"bogus"} is never generated by @code{yylex},
the added rule cannot alter the way actual input is parsed.
In this particular example, there is another way to solve the problem:
-rewrite the rule for @code{return_spec} to use @code{ID} directly
+rewrite the rule for @code{return_spec} to use @code{"id"} directly
instead of via @code{name}. This also causes the two confusing
contexts to have different sets of active rules, because the one for
@code{return_spec} activates the altered rule for @code{return_spec}
@@ -7203,7 +7297,7 @@ param_spec:
;
return_spec:
type
-| ID ':' type
+| "id" ':' type
;
@end example
@@ -12047,7 +12141,10 @@ London, Department of Computer Science, TR-00-12
(December 2000).
@c LocalWords: subdirectory Solaris nonassociativity perror schemas Malloy ints
@c LocalWords: Scannerless ispell american ChangeLog smallexample CSTYPE CLTYPE
@c LocalWords: clval CDEBUG cdebug deftypeopx yyterminate LocationType
address@hidden LocalWords: errorVerbose
address@hidden LocalWords: parsers parser's
address@hidden LocalWords: associativity subclasses precedences unresolvable
runnable
address@hidden LocalWords: allocators subunit initializations unreferenced
untyped
address@hidden LocalWords: errorVerbose subtype subtypes
@c Local Variables:
@c ispell-dictionary: "american"
diff --git a/tests/actions.at b/tests/actions.at
index ec88cb9..78977c8 100644
--- a/tests/actions.at
+++ b/tests/actions.at
@@ -73,8 +73,8 @@ AT_CLEANUP
## Initial location. ##
## ------------------ ##
-# AT_TEST(SKELETON-NAME, DIRECTIVES)
-# ----------------------------------
+# AT_TEST(SKELETON-NAME, DIRECTIVES, [MORE-DIRECTIVES], [LOCATION = 1.1])
+# -----------------------------------------------------------------------
# Check that the initial location is correct.
m4_pushdef([AT_TEST],
[AT_SETUP([Initial location: $1 $2])
@@ -85,7 +85,8 @@ AT_DATA_GRAMMAR([[input.y]],
%locations
%debug
%skeleton "$1"
-$2
+]$2[
+]$3[
%parse-param { int x } // Useless, but used to force yyerror purity.
%code
{
@@ -122,8 +123,8 @@ main (void)
AT_FULL_COMPILE([input])
AT_PARSER_CHECK([./input], 1, [],
-[[1.1
-1.1: syntax error
+[m4_default([$4], [1.1])
+m4_default([$4], [1.1])[: syntax error
]])
AT_BISON_OPTION_POPDEFS
AT_CLEANUP
@@ -138,6 +139,36 @@ AT_TEST([glr.c])
AT_TEST([lalr1.cc])
AT_TEST([glr.cc])
+## A very different test, based on PostgreSQL's implementation of the
+## locations. See
+## http://lists.gnu.org/archive/html/bug-bison/2012-11/msg00023.html
+##
+## Weirdly enough, to trigger the warning with GCC 4.7, we must not
+## use fprintf, so run the test twice: once to check the warning
+## (absence thereof), and another time to check the value.
+AT_TEST([yacc.c], [%define api.pure],
+[[%{
+# define YYLTYPE int
+# define YY_LOCATION_PRINT(Stream, Loc) \
+ (void) (Loc)
+# define YYLLOC_DEFAULT(Current, Rhs, N) \
+ (Current) = ((Rhs)[N ? 1 : 0])
+%}
+]],
+[@&address@hidden)
+
+AT_TEST([yacc.c], [%define api.pure],
+[[%{
+# define YYLTYPE int
+# define YY_LOCATION_PRINT(Stream, Loc) \
+ fprintf ((Stream), "%d", (Loc))
+# define YYLLOC_DEFAULT(Current, Rhs, N) \
+ (Current) = ((Rhs)[N ? 1 : 0])
+%}
+]],
+[0])
+
+
m4_popdef([AT_TEST])
and then into master as follows:
commit 589149dccf052e470b3991d9a79108ab8aac750c
Author: Akim Demaille <address@hidden>
Date: Mon Nov 26 09:49:23 2012 +0100
doc: use %precedence instead of nonassoc when associativity is not wanted
* doc/bison.texi: here.
Formatting changes in some grammars.
Fix a %prec into %precedence.
commit c6b1772473d0a26faa22464df98718d0d0ae2e2e
Merge: 06ec010 c6bf97c
Author: Akim Demaille <address@hidden>
Date: Mon Nov 26 09:14:51 2012 +0100
Merge remote-tracking branch 'origin/maint'
* origin/maint:
yacc.c: always initialize yylloc
scanner: issue a single error for groups of invalid characters
tests: formatting changes
doc: one of the fixes for an ambiguous grammar was ambiguous too
doc: fix the dangling else with precedence directives
doc: prefer "token" to TOKEN
doc: formatting changes
scanner: use explicit "ignore" statements
Conflicts:
src/scan-gram.l
diff --git a/NEWS b/NEWS
index f1ac888..c8cab5e 100644
--- a/NEWS
+++ b/NEWS
@@ -296,6 +296,17 @@ GNU Bison NEWS
Two nodes were added to the documentation: Xml and Graphviz.
+* Noteworthy changes in release ?.? (????-??-??) [?]
+
+** Bug fixes
+
+ Warnings about uninitialized yylloc in yyparse have been fixed.
+
+** Documentation
+
+ The sections about shift/reduce and reduce/reduce conflicts resolution
+ have been fixed and extended.
+
* Noteworthy changes in release 2.6.5 (2012-11-07) [stable]
We consider compiler warnings about Bison generated parsers to be bugs.
diff --git a/THANKS b/THANKS
index ec89536..0c6a817 100644
--- a/THANKS
+++ b/THANKS
@@ -1,8 +1,9 @@
Bison was originally written by Robert Corbett. It would not be what
it is today without the invaluable help of these people:
+Аскар Сафин address@hidden
Airy Andre address@hidden
-Akim Demaille address@hidden
+Akim Demaille address@hidden
Albert Chin-A-Young address@hidden
Alexander Belopolsky address@hidden
Alexandre Duret-Lutz address@hidden
@@ -89,6 +90,7 @@ Pascal Bart address@hidden
Paul Eggert address@hidden
Paul Hilfinger address@hidden
Per Allansson address@hidden
+Peter Eisentraut address@hidden
Peter Fales address@hidden
Peter Hamorsky address@hidden
Peter Simons address@hidden
diff --git a/data/yacc.c b/data/yacc.c
index ebc4127..3221840 100644
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -186,7 +186,8 @@ int yychar;
or non-GCC compilers. */
static YYSTYPE yyval_default;
# define YY_INITIAL_VALUE(Value) = Value
-#endif]])[
+#endif]b4_locations_if([[
+static YYLTYPE yyloc_default][]b4_yyloc_default[;]])])[
#ifndef YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
# define YY_IGNORE_MAYBE_UNINITIALIZED_BEGIN
# define YY_IGNORE_MAYBE_UNINITIALIZED_END
@@ -199,7 +200,7 @@ static YYSTYPE yyval_default;
YYSTYPE yylval YY_INITIAL_VALUE(yyval_default);]b4_locations_if([[
/* Location data for the lookahead symbol. */
-YYLTYPE yylloc][]b4_yyloc_default[;
+YYLTYPE yylloc]b4_pure_if([ = yyloc_default], [b4_yyloc_default])[;
]])b4_pure_if([], [[
/* Number of syntax errors so far. */
@@ -1307,7 +1308,8 @@ b4_function_define([[yyparse]], [[int]], b4_parse_param)[
yypstate *yyps_local;]b4_pure_if([[
int yychar;
YYSTYPE yylval;]b4_locations_if([[
- YYLTYPE yylloc][]b4_yyloc_default[;]])])[
+ static YYLTYPE yyloc_default][]b4_yyloc_default[;
+ YYLTYPE yylloc = yyloc_default;]])])[
if (yyps)
yyps_local = yyps;
else
@@ -1451,8 +1453,7 @@ b4_function_define([[yyparse]], [[int]], b4_parse_param)[
yychar = YYEMPTY; /* Cause a token to be read. */
]m4_ifdef([b4_initial_action], [
b4_dollar_pushdef([m4_define([b4_dollar_dollar_used])yylval], [],
- [m4_define([b4_at_dollar_used])dnl
-b4_push_if([b4_pure_if([*])yypushed_loc], [yylloc])])dnl
+ [b4_push_if([b4_pure_if([*])yypushed_loc], [yylloc])])dnl
/* User initialization code. */
b4_user_initial_action
b4_dollar_popdef[]dnl
diff --git a/doc/bison.texi b/doc/bison.texi
index 6a35422..31a46ed 100644
--- a/doc/bison.texi
+++ b/doc/bison.texi
@@ -280,6 +280,7 @@ Operator Precedence
* Precedence Only:: How to specify precedence only.
* Precedence Examples:: How these features are used in the previous example.
* How Precedence:: How they work.
+* Non Operators:: Using precedence for general conflicts.
Tuning LR
@@ -895,10 +896,7 @@ parses a vastly simplified form of Pascal type
declarations.
@end group
%%
-
address@hidden
type_decl: TYPE ID '=' type ';' ;
address@hidden group
@group
type:
@@ -1868,9 +1866,7 @@ here is the definition we will use:
@comment file: rpcalc.y
@example
address@hidden
#include <stdio.h>
address@hidden group
@group
/* Called by yyparse on error. */
@@ -2640,9 +2636,7 @@ operators in @code{yylex}.
@comment file: mfcalc.y: 3
@example
address@hidden
#include <ctype.h>
address@hidden group
@group
int
@@ -3394,9 +3388,7 @@ one of your tokens with a @code{%token} declaration.
A Bison grammar rule has the following general form:
@example
address@hidden
@var{result}: @address@hidden;
address@hidden group
@end example
@noindent
@@ -3407,9 +3399,7 @@ are put together by this rule (@pxref{Symbols}).
For example,
@example
address@hidden
exp: exp '+' exp;
address@hidden group
@end example
@noindent
@@ -3713,9 +3703,7 @@ difference with tools like Flex, for which @samp{|}
stands for either
following example, the action is triggered only when @samp{b} is found:
@example
address@hidden
a-or-b: 'a'|'b' @{ a_or_b_found = 1; @};
address@hidden group
@end example
@cindex default action
@@ -6875,7 +6863,7 @@ expr:
term:
'(' expr ')'
| term '!'
-| NUMBER
+| "number"
;
@end group
@end example
@@ -6914,20 +6902,20 @@ statements, with a pair of rules like this:
@example
@group
if_stmt:
- IF expr THEN stmt
-| IF expr THEN stmt ELSE stmt
+ "if" expr "then" stmt
+| "if" expr "then" stmt "else" stmt
;
@end group
@end example
@noindent
-Here we assume that @code{IF}, @code{THEN} and @code{ELSE} are
-terminal symbols for specific keyword tokens.
+Here @code{"if"}, @code{"then"} and @code{"else"} are terminal symbols for
+specific keyword tokens.
-When the @code{ELSE} token is read and becomes the lookahead token, the
+When the @code{"else"} token is read and becomes the lookahead token, the
contents of the stack (assuming the input is valid) are just right for
reduction by the first rule. But it is also legitimate to shift the
address@hidden, because that would lead to eventual reduction by the second
address@hidden"else"}, because that would lead to eventual reduction by the
second
rule.
This situation, where either a shift or a reduction would be valid, is
@@ -6936,14 +6924,14 @@ these conflicts by choosing to shift, unless otherwise
directed by
operator precedence declarations. To see the reason for this, let's
contrast it with the other alternative.
-Since the parser prefers to shift the @code{ELSE}, the result is to attach
+Since the parser prefers to shift the @code{"else"}, the result is to attach
the else-clause to the innermost if-statement, making these two inputs
equivalent:
@example
-if x then if y then win (); else lose;
+if x then if y then win; else lose;
-if x then do; if y then win (); else lose; end;
+if x then do; if y then win; else lose; end;
@end example
But if the parser chose to reduce when possible rather than shift, the
@@ -6951,9 +6939,9 @@ result would be to attach the else-clause to the
outermost if-statement,
making these two inputs equivalent:
@example
-if x then if y then win (); else lose;
+if x then if y then win; else lose;
-if x then do; if y then win (); end; else lose;
+if x then do; if y then win; end; else lose;
@end example
The conflict exists because the grammar as written is ambiguous: either
@@ -6966,11 +6954,16 @@ This particular ambiguity was first encountered in the
specifications of
Algol 60 and is called the ``dangling @code{else}'' ambiguity.
To avoid warnings from Bison about predictable, legitimate shift/reduce
-conflicts, use the @code{%expect @var{n}} declaration.
+conflicts, you can use the @code{%expect @var{n}} declaration.
There will be no warning as long as the number of shift/reduce conflicts
is exactly @var{n}, and Bison will report an error if there is a
different number.
address@hidden Decl, ,Suppressing Conflict Warnings}.
address@hidden Decl, ,Suppressing Conflict Warnings}. However, we don't
+recommend the use of @code{%expect} (except @samp{%expect 0}!), as an equal
+number of conflicts does not mean that they are the @emph{same}. When
+possible, you should rather use precedence directives to @emph{fix} the
+conflicts explicitly (@pxref{Non Operators,, Using Precedence For Non
+Operators}).
The definition of @code{if_stmt} above is solely to blame for the
conflict, but the conflict does not actually appear without additional
@@ -6978,10 +6971,7 @@ rules. Here is a complete Bison grammar file that
actually manifests
the conflict:
@example
address@hidden
-%token IF THEN ELSE variable
%%
address@hidden group
@group
stmt:
expr
@@ -6991,13 +6981,13 @@ stmt:
@group
if_stmt:
- IF expr THEN stmt
-| IF expr THEN stmt ELSE stmt
+ "if" expr "then" stmt
+| "if" expr "then" stmt "else" stmt
;
@end group
expr:
- variable
+ "identifier"
;
@end example
@@ -7017,6 +7007,7 @@ shift and when to reduce.
* Precedence Only:: How to specify precedence only.
* Precedence Examples:: How these features are used in the previous example.
* How Precedence:: How they work.
+* Non Operators:: Using precedence for general conflicts.
@end menu
@node Why Precedence
@@ -7155,16 +7146,11 @@ would declare them in groups of equal precedence. For
example, @code{'+'} is
declared with @code{'-'}:
@example
-%left '<' '>' '=' NE LE GE
+%left '<' '>' '=' "!=" "<=" ">="
%left '+' '-'
%left '*' '/'
@end example
address@hidden
-(Here @code{NE} and so on stand for the operators for ``not equal''
-and so on. We assume that these tokens are more than one character long
-and therefore are represented by names, not character literals.)
-
@node How Precedence
@subsection How Precedence Works
@@ -7187,6 +7173,44 @@ resolved.
Not all rules and not all tokens have precedence. If either the rule or
the lookahead token has no precedence, then the default is to shift.
address@hidden Non Operators
address@hidden Using Precedence For Non Operators
+
+Using properly precedence and associativity directives can help fixing
+shift/reduce conflicts that do not involve arithmetics-like operators. For
+instance, the ``dangling @code{else}'' problem (@pxref{Shift/Reduce, ,
+Shift/Reduce Conflicts}) can be solved elegantly in two different ways.
+
+In the present case, the conflict is between the token @code{"else"} willing
+to be shifted, and the rule @samp{if_stmt: "if" expr "then" stmt}, asking
+for reduction. By default, the precedence of a rule is that of its last
+token, here @code{"then"}, so the conflict will be solved appropriately
+by giving @code{"else"} a precedence higher than that of @code{"then"}, for
+instance as follows:
+
address@hidden
address@hidden
+%precedence "then"
+%precedence "else"
address@hidden group
address@hidden example
+
+Alternatively, you may give both tokens the same precedence, in which case
+associativity is used to solve the conflict. To preserve the shift action,
+use right associativity:
+
address@hidden
+%right "then" "else"
address@hidden example
+
+Neither solution is perfect however. Since Bison does not provide, so far,
+``scoped'' precedence, both force you to declare the precedence
+of these keywords with respect to the other operators your grammar.
+Therefore, instead of being warned about new conflicts you would be unaware
+of (e.g., a shift/reduce conflict due to @samp{if test then 1 else 2 + 3}
+being ambiguous: @samp{if test then 1 else (2 + 3)} or @samp{(if test then 1
+else 2) + 3}?), the conflict will be already ``fixed''.
+
@node Contextual Precedence
@section Context-Dependent Precedence
@cindex context-dependent precedence
@@ -7347,30 +7371,38 @@ reduce/reduce conflict must be studied and usually
eliminated. Here is the
proper way to define @code{sequence}:
@example
address@hidden
sequence:
/* empty */ @{ printf ("empty sequence\n"); @}
| sequence word @{ printf ("added word %s\n", $2); @}
;
address@hidden group
@end example
Here is another common error that yields a reduce/reduce conflict:
@example
address@hidden
sequence:
/* empty */
| sequence words
| sequence redirects
;
address@hidden group
address@hidden
words:
/* empty */
| words word
;
address@hidden group
address@hidden
redirects:
/* empty */
| redirects redirect
;
address@hidden group
@end example
@noindent
@@ -7423,6 +7455,58 @@ redirects:
@end group
@end example
+Yet this proposal introduces another kind of ambiguity! The input
address@hidden word} can be parsed as a single @code{words} composed of two
address@hidden, or as two address@hidden @code{words} (and likewise for
address@hidden/@code{redirects}). However this ambiguity is now a
+shift/reduce conflict, and therefore it can now be addressed with precedence
+directives.
+
+To simplify the matter, we will proceed with @code{word} and @code{redirect}
+being tokens: @code{"word"} and @code{"redirect"}.
+
+To prefer the longest @code{words}, the conflict between the token
address@hidden"word"} and the rule @samp{sequence: sequence words} must be
resolved
+as a shift. To this end, we use the same techniques as exposed above, see
address@hidden Operators,, Using Precedence For Non Operators}. One solution
+relies on precedences: use @code{%prec} to give a lower precedence to the
+rule:
+
address@hidden
+%precedence "word"
+%precedence "sequence"
+%%
address@hidden
+sequence:
+ /* empty */
+| sequence word %prec "sequence"
+| sequence redirect %prec "sequence"
+;
address@hidden group
+
address@hidden
+words:
+ word
+| words "word"
+;
address@hidden group
address@hidden example
+
+Another solution relies on associativity: provide both the token and the
+rule with the same precedence, but make them right-associative:
+
address@hidden
+%right "word" "redirect"
+%%
address@hidden
+sequence:
+ /* empty */
+| sequence word %prec "word"
+| sequence redirect %prec "redirect"
+;
address@hidden group
address@hidden example
+
@node Mysterious Conflicts
@section Mysterious Conflicts
@cindex Mysterious Conflicts
@@ -7432,8 +7516,6 @@ Here is an example:
@example
@group
-%token ID
-
%%
def: param_spec return_spec ',';
param_spec:
@@ -7441,17 +7523,18 @@ param_spec:
| name_list ':' type
;
@end group
+
@group
return_spec:
type
| name ':' type
;
@end group
+
+type: "id";
+
@group
-type: ID;
address@hidden group
address@hidden
-name: ID;
+name: "id";
name_list:
name
| name ',' name_list
@@ -7459,16 +7542,16 @@ name_list:
@end group
@end example
-It would seem that this grammar can be parsed with only a single token
-of lookahead: when a @code{param_spec} is being read, an @code{ID} is
-a @code{name} if a comma or colon follows, or a @code{type} if another
address@hidden follows. In other words, this grammar is LR(1).
+It would seem that this grammar can be parsed with only a single token of
+lookahead: when a @code{param_spec} is being read, an @code{"id"} is a
address@hidden if a comma or colon follows, or a @code{type} if another
address@hidden"id"} follows. In other words, this grammar is LR(1).
@cindex LR
@cindex LALR
However, for historical reasons, Bison cannot by default handle all
LR(1) grammars.
-In this grammar, two contexts, that after an @code{ID} at the beginning
+In this grammar, two contexts, that after an @code{"id"} at the beginning
of a @code{param_spec} and likewise at the beginning of a
@code{return_spec}, are similar enough that Bison assumes they are the
same.
@@ -7499,41 +7582,43 @@ distinct. In the above example, adding one rule to
@example
@group
-%token BOGUS
address@hidden
-%%
@dots{}
return_spec:
type
| name ':' type
-| ID BOGUS /* This rule is never used. */
+| "id" "bogus" /* This rule is never used. */
;
@end group
@end example
This corrects the problem because it introduces the possibility of an
-additional active rule in the context after the @code{ID} at the beginning of
+additional active rule in the context after the @code{"id"} at the beginning of
@code{return_spec}. This rule is not active in the corresponding context
in a @code{param_spec}, so the two contexts receive distinct parser states.
-As long as the token @code{BOGUS} is never generated by @code{yylex},
+As long as the token @code{"bogus"} is never generated by @code{yylex},
the added rule cannot alter the way actual input is parsed.
In this particular example, there is another way to solve the problem:
-rewrite the rule for @code{return_spec} to use @code{ID} directly
+rewrite the rule for @code{return_spec} to use @code{"id"} directly
instead of via @code{name}. This also causes the two confusing
contexts to have different sets of active rules, because the one for
@code{return_spec} activates the altered rule for @code{return_spec}
rather than the one for @code{name}.
@example
address@hidden
param_spec:
type
| name_list ':' type
;
address@hidden group
+
address@hidden
return_spec:
type
-| ID ':' type
+| "id" ':' type
;
address@hidden group
@end example
For a more detailed exposition of LALR(1) parsers and parser
@@ -7638,7 +7723,8 @@ There are at least two scenarios where LALR can be
worthwhile:
@cindex GLR with LALR
When employing GLR parsers (@pxref{GLR Parsers}), if you do not resolve any
-conflicts statically (for example, with @code{%left} or @code{%prec}), then
+conflicts statically (for example, with @code{%left} or @code{%precedence}),
+then
the parser explores all potential parses of any given input. In this case,
the choice of parser table construction algorithm is guaranteed not to alter
the language accepted by the parser. LALR parser tables are the smallest
@@ -12746,7 +12832,10 @@ London, Department of Computer Science, TR-00-12
(December 2000).
@c LocalWords: subdirectory Solaris nonassociativity perror schemas Malloy ints
@c LocalWords: Scannerless ispell american ChangeLog smallexample CSTYPE CLTYPE
@c LocalWords: clval CDEBUG cdebug deftypeopx yyterminate LocationType
address@hidden LocalWords: errorVerbose
address@hidden LocalWords: parsers parser's
address@hidden LocalWords: associativity subclasses precedences unresolvable
runnable
address@hidden LocalWords: allocators subunit initializations unreferenced
untyped
address@hidden LocalWords: errorVerbose subtype subtypes
@c Local Variables:
@c ispell-dictionary: "american"
diff --git a/gnulib b/gnulib
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit daf7f8c02242c535d596231e2f655109b97fa2bc
+Subproject commit daf7f8c02242c535d596231e2f655109b97fa2bc-dirty
diff --git a/src/scan-gram.l b/src/scan-gram.l
index 9812455..f5c9b88 100644
--- a/src/scan-gram.l
+++ b/src/scan-gram.l
@@ -131,8 +131,8 @@ static void unexpected_newline (boundary, char const *);
%x SC_BRACKETED_ID SC_RETURN_BRACKETED_ID
letter [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
+notletter [^.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]{-}[%\{]
id {letter}({letter}|[-0-9])*
-directive %{id}
int [0-9]+
/* POSIX says that a tag must be both an id and a C union member, but
@@ -184,7 +184,7 @@ eqopt ([[:space:]]*=)?
complain (loc, Wother, _("stray ',' treated as white space"));
}
[ \f\n\t\v] |
- "//".* ;
+ "//".* continue;
"/*" {
token_start = loc->start;
context_state = YY_START;
@@ -269,7 +269,7 @@ eqopt ([[:space:]]*=)?
"%pure"[-_]"parser" DEPRECATED("%pure-parser");
"%token"[-_]"table" DEPRECATED("%token-table");
- {directive} {
+ "%"{id}|"%"{notletter}([[:graph:]])+ {
complain (loc, complaint, _("invalid directive: %s"), quote (yytext));
}
@@ -353,8 +353,9 @@ eqopt ([[:space:]]*=)?
BEGIN SC_BRACKETED_ID;
}
- . {
- complain (loc, complaint, _("invalid character: %s"),
+ [^\[%A-Za-z0-9_<>{}\"\'*;|=/, \f\n\t\v]+|. {
+ complain (loc, complaint, "%s: %s",
+ ngettext ("invalid character", "invalid characters", yyleng),
quote_mem (yytext, yyleng));
}
@@ -449,10 +450,14 @@ eqopt ([[:space:]]*=)?
else
complain (loc, complaint, _("an identifier expected"));
}
- . {
- complain (loc, complaint, _("invalid character in bracketed name: %s"),
+
+ [^\].A-Za-z0-9_/ \f\n\t\v]+|. {
+ complain (loc, complaint, "%s: %s",
+ ngettext ("invalid character in bracketed name",
+ "invalid characters in bracketed name", yyleng),
quote_mem (yytext, yyleng));
}
+
<<EOF>> {
BEGIN bracketed_id_context_state;
unexpected_eof (bracketed_id_start, "]");
@@ -479,7 +484,7 @@ eqopt ([[:space:]]*=)?
<SC_YACC_COMMENT>
{
"*/" BEGIN context_state;
- .|\n ;
+ .|\n continue;
<<EOF>> unexpected_eof (token_start, "*/"); BEGIN context_state;
}
diff --git a/tests/actions.at b/tests/actions.at
index 01fecc6..099237c 100644
--- a/tests/actions.at
+++ b/tests/actions.at
@@ -73,8 +73,8 @@ AT_CLEANUP
## Initial location. ##
## ------------------ ##
-# AT_TEST(SKELETON-NAME, DIRECTIVES)
-# ----------------------------------
+# AT_TEST(SKELETON-NAME, DIRECTIVES, [MORE-DIRECTIVES], [LOCATION = 1.1])
+# -----------------------------------------------------------------------
# Check that the initial location is correct.
m4_pushdef([AT_TEST],
[AT_SETUP([Initial location: $1 $2])
@@ -85,7 +85,8 @@ AT_DATA_GRAMMAR([[input.y]],
%locations
%debug
%skeleton "$1"
-$2
+]$2[
+]$3[
%parse-param { int x } // Useless, but used to force yyerror purity.
%code
{
@@ -122,8 +123,8 @@ main (void)
AT_FULL_COMPILE([input])
AT_PARSER_CHECK([./input], 1, [],
-[[1.1
-1.1: syntax error
+[m4_default([$4], [1.1])
+m4_default([$4], [1.1])[: syntax error
]])
AT_BISON_OPTION_POPDEFS
AT_CLEANUP
@@ -138,6 +139,36 @@ AT_TEST([glr.c])
AT_TEST([lalr1.cc])
AT_TEST([glr.cc])
+## A very different test, based on PostgreSQL's implementation of the
+## locations. See
+## http://lists.gnu.org/archive/html/bug-bison/2012-11/msg00023.html
+##
+## Weirdly enough, to trigger the warning with GCC 4.7, we must not
+## use fprintf, so run the test twice: once to check the warning
+## (absence thereof), and another time to check the value.
+AT_TEST([yacc.c], [%define api.pure],
+[[%{
+# define YYLTYPE int
+# define YY_LOCATION_PRINT(Stream, Loc) \
+ (void) (Loc)
+# define YYLLOC_DEFAULT(Current, Rhs, N) \
+ (Current) = ((Rhs)[N ? 1 : 0])
+%}
+]],
+[@&address@hidden)
+
+AT_TEST([yacc.c], [%define api.pure],
+[[%{
+# define YYLTYPE int
+# define YY_LOCATION_PRINT(Stream, Loc) \
+ fprintf ((Stream), "%d", (Loc))
+# define YYLLOC_DEFAULT(Current, Rhs, N) \
+ (Current) = ((Rhs)[N ? 1 : 0])
+%}
+]],
+[0])
+
+
m4_popdef([AT_TEST])
diff --git a/tests/input.at b/tests/input.at
index f7f5adf..98a6784 100644
--- a/tests/input.at
+++ b/tests/input.at
@@ -39,11 +39,7 @@ default: 'a' }
AT_CHECK([[$PERL -pi -e 's/\\(\d{3})/chr(oct($1))/ge' input.y || exit 77]])
AT_BISON_CHECK([input.y], [1], [],
-[[input.y:1.1: error: invalid character: '\0'
-input.y:1.1: error: invalid character: '\001'
-input.y:1.1: error: invalid character: '\002'
-input.y:1.1: error: invalid character: '\377'
-input.y:1.2: error: invalid character: '?'
+[[input.y:1.1-2: error: invalid characters: '\0\001\002\377?'
input.y:3.1: error: invalid character: '?'
input.y:4.14: error: invalid character: '}'
input.y:5.1: error: invalid character: '%'
diff --git a/tests/named-refs.at b/tests/named-refs.at
index 8c0fbb9..ea37922 100644
--- a/tests/named-refs.at
+++ b/tests/named-refs.at
@@ -55,12 +55,12 @@ static int power (int base, int exponent);
%%
input:
line
-| input line { }
+| input line {}
;
line:
'\n'
-| exp '\n' { }
+| exp '\n' {}
;
exp:
@@ -72,12 +72,12 @@ exp:
$$ = $l;
}
| exp[x] '+' { $<ival>$ = $x; } [l] exp[r] { $$ = $<ival>l + $r; }
-| exp[l] '-' exp[r] { $$ = $l - $r; }
-| exp[l] '*' exp[r] { $$ = $l * $r; }
+| exp[l] '-' exp[r] { $$ = $l - $r; }
+| exp[l] '*' exp[r] { $$ = $l * $r; }
| exp[l] '/' exp[r] { $$ = $l / $r; }
| '-' exp %prec NEG { $$ = -$2; }
-| exp[l] '^' exp[r] { $$ = power ($l, $r); }
-| '(' exp[e] ')' { $$ = $e; }
+| exp[l] '^' exp[r] { $$ = power ($l, $r); }
+| '(' exp[e] ')' { $$ = $e; }
| '(' error ')' { $$ = 1111; yyerrok; }
| '!' { $$ = 0; YYERROR; }
| '-' error { $$ = 0; YYERROR; }
@@ -220,12 +220,12 @@ static int power (int base, int exponent);
%%
input:
line
-| input line { }
+| input line {}
;
line:
'\n'
-| exp '\n' { }
+| exp '\n' {}
;
exp:
@@ -241,7 +241,7 @@ exp:
| exp[x] '*' { $<ival>$ = $x; } [l] exp[r] { $$ = $l * $r; }
| exp[l] '/' exp[r] { $$ = $l / $r; }
| '-' exp %prec NEG { $$ = -$2; }
-| exp[l] '^' exp[r] { $$ = power ($l, $r12); }
+| exp[l] '^' exp[r] { $$ = power ($l, $r12); }
| '(' exp ')' { $$ = $expo; }
| '(' error ')' { $$ = 1111; yyerrok; }
| '!' { $$ = 0; YYERROR; }
@@ -258,8 +258,8 @@ test.y:42.1-3: refers to: $exp at $$
test.y:51.7: possibly meant: $x, hiding $exp at $1
test.y:51.41: possibly meant: $r, hiding $exp at $4
test.y:52.51-52: error: $l of 'exp' has no declared type
-test.y:55.46-49: error: invalid reference: '$r12'
-test.y:55.3-53: symbol not found in production: r12
+test.y:55.40-43: error: invalid reference: '$r12'
+test.y:55.3-47: symbol not found in production: r12
test.y:56.29-33: error: invalid reference: '$expo'
test.y:56.3-46: symbol not found in production: expo
]])
@@ -443,19 +443,14 @@ AT_SETUP([Stray symbols in brackets])
AT_DATA_GRAMMAR([test.y],
[[
%%
-start: foo[ /* aaa */ *&-.+\000\001\002\377 ] bar
+start: foo[ % /* aaa */ *&-.+\000\001\002\377 ] bar
{ s = $foo; }
]])
AT_CHECK([[$PERL -pi -e 's/\\(\d{3})/chr(oct($1))/ge' test.y || exit 77]])
AT_BISON_CHECK([-o test.c test.y], 1, [],
-[[test.y:11.23: error: invalid character in bracketed name: '*'
-test.y:11.24: error: invalid character in bracketed name: '&'
-test.y:11.25: error: invalid character in bracketed name: '-'
-test.y:11.27: error: invalid character in bracketed name: '+'
-test.y:11.28: error: invalid character in bracketed name: '\0'
-test.y:11.28: error: invalid character in bracketed name: '\001'
-test.y:11.28: error: invalid character in bracketed name: '\002'
-test.y:11.28: error: invalid character in bracketed name: '\377'
+[[test.y:11.13: error: invalid character in bracketed name: '%'
+test.y:11.25-27: error: invalid characters in bracketed name: '*&-'
+test.y:11.29-30: error: invalid characters in bracketed name: '+\0\001\002\377'
]])
AT_CLEANUP